Fire extinguisher



May 29, 1951 R. w. AUSTIN FIRE EXTINGUISHER Filed April 9, 1949 INVENTOR. @{5/1 14 405%? ATTO F/V P' Patentecl May 29, 1951 UNITED STATES. PATENT OFFICE FIRE EXTINGUISHER Ralph W. Austin, Weymouth, Mass., assignor to Knight and Thomas Incorporated, Somerville, Mass, a corporation of Massachusetts Application April 9, 1949, Serial No. 86,500

1 Claim. 1

This invention relates to a fire extinguisher.

The object of the invention is to provide a novel fire extinguisher which may be used with advantage in substitution for the usual sodaacid type of fire extinguisher now extensively used and whose construction is such as to avoid the necessity for annual recharging of the extinguisher.

With this general object in view and such others as may hereinafter appear, the invention consists in the fire extinguisher hereinafter described and particularly defined in the claim at the end of this specification.

The drawing illustrates, in side elevation with portions in section, a fire extinguisher embodying the invention.

The so-called soda-acid type of fire extinguishers which are now in general use have certain shortcomings, and as a result the fire underwriters require that such extinguishers be recharged annually. The bicarbonate of soda solution which is utilized in the extinguisher is estimated to deteriorate in carbon dioxide generating efficiency in amount of about 20% each year, and the sulphuric acid utilized in the extinguisher absorbs water, becoming more dilute and as a result, an annual recharge of such fire extinguishers has been required in order to keep themat the desired operating efiiciency.

The present invention contemplates the provision of a fire extinguisher which may be used commercially as a substitute for an extinguisher of the soda-acid type and used for all of the purposes for which soda-acid types are now used, and which is characterized by its ability to remain in a satisfactory operating condition without recharging for a period of at least three years.

Referring now to the drawing, It represents the body portion of the fire extinguisher casing which is provided with the usual threaded neck portion I2 upon which the usual cap member I4 is screwed as illustrated. The cap I4 is arranged to clamp an acid bottle supporting cage 3 in operative position in the mouth or upper portion of the extinguisher. As herein shown, the cage is provided with a flange 2B which is clamped down upon the upper edge of the neck portion [2 of the extinguisher by the ca 14. The acid bottle supporting cage is provided with the usual openings 22, 24 through which the carbonate solution 26 may pass to mix with the acid upon inversion of the extinguisher. The acid indicated at 30 is contained within an acid bottle 32 whose upper end is normally closed by a stopper 34 retained in operative relation by guides 36 depending from the underside of the cap. The structural features of the body portion, cage l8, acid bottle 32, stopper 34 and guides 35 may comprise those now embodied in commercial forms of soda-acid types of fire extinguishers.

The soda and acid type of extinguisher now upon the market utilizes about one and one-half pounds of bicarbonate of soda to two and onehalf gallons of water in the fire extinguishing charge. I have found that an extinguisher embodying the present invention may be produced having all of the characteristics and efiiciencies of a soda-acid type of extinguisherby dissolving four pounds of potassium carbonate in two and one-half gallons of water to produce the fire extinguishing charge, such solution being contained within the body portion In of the extinguisher. It has been found from experience that such a potassium carbonate solution does not deteriorate for relatively long periods of time and the extinguisher remains in a satisfactory operating condition for a period of at least three years. The acid solution utilized within the acid bottle 32 comprises a strong sulphuric acid preferably in amount of four ounces based upon the foregoing amount of potassium carbonate, and in accordance with the invention, the acid is prevented from dilution by the absorption of water by being sealed with a moderate amount of acetylene tetrachloride, such sealing layer being indicated at 40 in the drawing.

The present extinguisher charge has a freezing point substantially lower than that of the bicarbonate of soda solution heretofore utilized in the soda-acid type of extinguisher, and is capable of use under conditions of temperature as low as 18 F. In this respect, the present extinguisher shows a much wider range of utility over the prior soda-acid type, but the principal advantageous result flowing from the present invention resides in the stability of the present extinguisher charge over long periods of time. As a result, the necessity for recharging the extinguisher to maintain it in a satisfactory operating condition is extended to a period of three years instead of the annual recharge required with the present soda-acid type of extinguisher.

Having thus described the invention, what is claimed is:

A fire extinguisher having an extinguisher casing, an acid container operatively supported therein in an upright position and containing a body of acid, a liquid seal for the acid comprising a layer of acetylene tetrachloride and a fire ex- 4 REFERENCES CITED The following references are of record in the file of this patent:

5 UNITED STATES PATENTS Number Name Date 1,499,631 Austin July 1, 1924 ,58 5% us Ap 2'1. 1926 

